1. Field of the Invention
The present invention is directed to a cooling unit for power semiconductors.
1. Description of the Prior Art
U.S. Pat. No. 5,113,145 discloses a cooling unit for a number of parallel-connected transistors, whereby the transistors are each respectively secured on a thermally and electrically conductive ring. The transistors are rotationally symmetrically distributed on this ring and are electrically connected thereto by respective terminals. The connections to further terminals of the transistors essentially ensue rotationally-symmetrically by means of large-area printed circuit boards. The ring is air-cooled. Due to the rotational-symmetrical arrangement, a uniform distribution of current to the transistors is assured. The mechanical structure, however, is complicated and can only be economically realized for limited dissipated powers. Moreover, modifying this arrangement to achieve a modular structure, as is often desirable, could be done, if at all, only with great difficulty.
German OS 36 15 782 discloses an arrangement of power transistors arranged in two rows lying opposite one another. All transistors are arranged on a common cooling member which for heat elimination, is secured on a further, ribbed cooling member by mounting screws. Again, only a limited heat elimination is possible with this structure.
German OS 42 17 289 discloses a cooling means wherein a number of semiconductor components are arranged in a cooling channel following one another. In order to improve the heat transmission between the surfaces of the semiconductor components to be cooled and a coolant flowing in the channel, each semiconductor component has at least one side exposed directly to the forced coolant flow in the cooling channel. For reducing the fluid friction, further, this side is provided with a profiled surface microstructure.
German OS 41 31 739 discloses a cooling means for electrical components, wherein corrugated plates are provided in a cooling channel for producing turbulence in a flowing coolant. Heat elimination is stated to be improved as a result of the turbulence.